Cebu earthquake caused by fault that had not moved for 400 years — PHIVOLCS

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) on Wednesday identified the fault that caused the 6.9-magnitude earthquake in Bogo City, Cebu on Tuesday that left 63 people dead.

At a press conference, PHIVOLCS Seismological Observation and Earthquake Prediction Division chief Dr. Winchelle Ian Sevilla said it was an offshore fault that had not moved in the epicentral area for at least 400 years.

“At least in the last 400 years, iyong pong fault na nag-generate dito ngayon lang po ulit siya gumalaw. So medyo matagal po siya gumalaw kaya siya medyo malakas. Based po ito sa ating catalogue,” Sevilla said.

(At least in the last 400 years, the fault that generated the earthquake there only moved again now. So it took a long time to move, that is why it was strong. This is based on our catalogue.)

“Sa ngayon po tinatawag nating 'offshore fault' kasi po nasa dagat. Kaya po tayo nag-deploy ng quick response team para lubos po nating maunawaan...Sa ngayon, wala pa pong pangalan,” he added.

(Right now we call it an 'offshore fault' because it is located in the sea. That is why we have deployed a quick response team so that we can fully understand it...Right now, there is no name for it.)

Cebu and nearby provinces are located in one of the seismically active regions in the country, according to PHIVOLCS.

Aside from earthquake sources such as the Bogo Fault, Daanbantayan Lineament, and Cebu Fault System, PHIVOLCS noted that there are also “local inland and offshore faults, some concealed by recent deposits, capable of generating earthquakes ranging from minor to strong magnitudes.”

At least eight significant earthquakes with magnitudes ranging from 5.0 to 7.2 had affected Cebu and nearby provinces in the past between 1885 and 2013, PHIVOLCS said.

These include the magnitude 6.9 event in Negros Oriental on February 6, 2012 and the magnitude 7.2 event in Bohol on October 15, 2013. —RF, GMA Integrated News